1. Field of the Invention
The present invention relates to a printing apparatus, and more particularly relates to a process for resetting the printing apparatus, and to a method for cleaning the print head of an ink jet type printing apparatus.
2. Description of the Related Art
Printers and other types of information processing devices typically implement a specific initialization process when a reset signal is asserted. The reset signal can be a power-on reset signal, which is asserted when the power is turned on, or a reset signal sent through an interface to the printing apparatus by a host computer, for example.
With a power-on reset, the power switch has typically been turned off at some point prior to being turned on. In many newer model printers, the power supply is not interrupted immediately when the power switch is turned off, but instead is interrupted after waiting a predetermined delay period. The printing apparatus also typically performs a particular process during this delay period (simply called a xe2x80x9cshutdown processxe2x80x9d below). This shutdown process can include, for example, initializing certain mechanical parts, such as the moving of the print head to a retracted position, and the backing up of processed data or maintenance data such as certain counter and time values. See, for example, JP-A-56-124977, JP-A-61-233819, JP-A-2-93811, JP-A-4-288274, and JP-A-7-261888. Such shutdown processes enable processed information or states stored when the power switch was turned off to be reflected in printer operation when the power switch is turned on again.
When a reset signal is issued from a host computer or other connected device, however, the reset operation is executed immediately to reinitialize the printing apparatus. As a result, the shutdown process implemented when the power switch is turned off cannot be executed. Some of the problems associated with this reset method when applied in an ink jet printer are described further below.
Ink jet printers, which print by ejecting ink from an ink jet head onto a print medium, require regular maintenance; that is, they require the cleaning of the ink jet head nozzles in order to sustain reliable ink jet head operation. Such regular cleaning is needed to prevent such problems as clogged nozzles which results from the ink drying and becoming viscous inside the nozzles.
This cleaning process is generally managed based on a timer, and is implemented with different levels depending on how much time has passed since the last cleaning operation, and ink jet head capping. This means that storing this timer value when the power is turned off enables the next cleaning operation to be more appropriately performed. It is also possible to record such counter values as an ink end counter, which is indicative of how much ink remains, and a print pass counter, which is indicative of the print volume and can be used as a guide to mechanical parts wear. These counters are used as a guide to maintenance requirements, including parts replacement.
When POS printers, networked printers, and other printing apparatuses that are controlled by a host computer are remotely located, full remote control of printing apparatus operation must be possible. This includes the ability to control, by means of a reset signal asserted from the host computer, execution of an initialization process that is essentially the same as the initialization process performed in response to a reset signal as is generated when the power switch is turned on.
A reset signal can, however, be asserted at various times, including when the host computer is turned on, when the operating system boots up, when an application boots up, and when an application starts printing. As a result, multiple reset signals can be sent to the printer at relatively short intervals depending upon the computer type, application, and printer driver.
In such cases as mentioned above, conventional printers do not have the opportunity to store the counter values, time information, and other maintenance information, and this information is therefore lost. Cleaning and parts replacement may therefore not occur as needed, and problems with print quality and printer breakdown may result.
Loss of print quality has therefore been prevented by performing the head cleaning process at the initialization level every time a reset signal is received. This, however, consumes more ink than is really necessary, and thus increases the operating cost of the printer. The number of expended ink cartridges also increases, which is obviously not desirable in terms of resource conservation and environmental protection.
There is therefore a need for a printing apparatus capable of performing a process equivalent to the power-on reset operation when a reset signal is received from a host computer. There is a further need for a printing apparatus cleaning method whereby a process equivalent to the power-on reset operation can be performed when a reset signal is received from a host computer.
It is therefore an object of the present invention to overcome the aforementioned problems.
It is a further object of this invention to provide a printing apparatus and reset and cleaning control method therefor, wherein, when the printing apparatus receives a reset signal, it stores specific printing apparatus status information, performs a reset operation which is the same or similar to that performed in response to a power-on reset signal, reads the stored status information to select the most appropriate cleaning process level based on the stored information, and performs the selected cleaning process.
To accomplish this, a printing apparatus connected to a host computer for printing to a printing medium based on data received from the host computer comprises, according to the present invention, non-volatile memory, a control means, an initialization means, and a reset signal processing means. The nonvolatile memory stores printing apparatus status information. The control means controls printing apparatus operation, including writing and reading information to said non-volatile memory. The initialization means reads specific status information written to the non-volatile memory and effects an initialization process according to a reset signal from the host computer or printing apparatus power on operation. The reset signal processing means receives a reset signal from the host computer, applies an external reset signal to the control means to inform the control means that a reset signal was received, and then applies an internal reset signal to the control means after a specific delay from applying the external reset signal. Thus informed that a reset signal was received, the control means writes at least the printing apparatus status information required for the initialization process to non-volatile memory during the period between when the external reset signal and internal reset signal are applied.
A printing apparatus according to an alternative version of the present invention comprises an ink jet head cleaning mechanism, non-volatile memory, a control means, and a reset signal processing means. The non-volatile memory stores printing apparatus status information. The control means controls printing apparatus operation, including writing and reading information to said non-volatile memory, and controls the cleaning mechanism using one of a plurality of process levels each consuming a different amount of ink. The reset signal processing means receives a reset signal from an external source, applies an external reset signal to the control means to inform the control means that an external reset signal was received, and then applies an internal reset signal to the control means after a specific delay from applying the external reset signal. The internal reset signal used here is the same as the reset signal applied when printing apparatus power is turned on. Thus informed that a reset signal was received, the control means writes the printing apparatus status information to non-volatile memory during the period between when the external reset signal and the internal reset signal are applied. After the internal reset signal is applied, the control means reads the printing apparatus status information stored to non-volatile memory, selects a specific process level based on the read information, and controls the cleaning mechanism according to the selected process level.
The present invention further addresses the above-stated needs by providing a control method for resetting a printing apparatus. This control method comprises an initialization step, a read initialization step, a notification step, a status information storage step, and an internal reset signal step. The initialization step initializes a non-volatile memory for storing printing apparatus status information, and a control means for controlling printing apparatus operation, including writing and reading information to said non-volatile memory. The read initialization step reads specific status information written to memory according to a reset signal from a host computer or printing apparatus power on operation. The notification step receives said reset signal, and applies an external reset signal to the control means to inform the control means that a reset signal was received. The status information storage step stores at least printing apparatus status information required for the initialization process to memory. The internal reset signal step applies an internal reset signal to the control means after a specific delay from applying the external reset signal.
A control method according to a further version of the invention comprises an initialization step, a notification step, a status information storage step, an internal reset signal step, a process level selection step, and a control step. The initialization step initializes an ink jet head cleaning mechanism, memory for storing printing apparatus status information, and a control means for controlling printing apparatus operation, including writing and reading information to said memory, and controlling the cleaning mechanism using one of a plurality of process levels each consuming a different amount of ink. The notification step receives said reset signal, and applies an external reset signal to the control means to inform the control means that a reset signal was received. The status information storage step stores printing apparatus status information to memory. The internal reset signal step applies an internal reset signal to the control means after a specific delay from applying the external reset signal. This internal reset signal is the same as the reset signal applied when printing apparatus power is turned on. The process level selection step reads printing apparatus status information stored to memory, and selects a specific process level based on the read information. The control step controls the cleaning mechanism according to the selected specific process level.
These and other objects and features of the present invention will be readily understood from the following detailed description taken in conjunction with preferred embodiments thereof with reference to the accompanying drawings, in which like parts are designated by like reference numerals and in which: